He had to retrieve stars from hatches in huge tanks as water rose up around him.

The challenge was stopped twice as the water got higher and Hugo could not find the stars because they had become stuck in S bends.

He stayed in the tank as the game was first halted for four minutes while rangers tried to find out where the star had got stuck.

When it happened again, producers stopped the trial and he climbed out of the tank with seven stars, thinking it was over. But bosses decided it was not fair if a star had not actually made it into the tank.

So after he stood for six minutes dripping wet, producers chucked a star into the top of the tank and Hugo got back in and found it.

He also banged his head during the trial, causing Ant and Dec some concern – but he insisted he was fine and carried on.

A show insider said: “It was one of our most expensive trials to build. We couldn’t believe it when it went wrong but we had to give Hugo the chance to win all of the stars.”